Method and apparatus for producing fibrous material



1940- J. H. THOMAS ET AL 19, 46

METHOD AND APPARATUS FOR PRODUCING FIBROUS MATERIAL Original Filed Aug.19, 1936 Jafizz [Z Thomas,

5:01:75 ML 51717517. 1 mmvrom:

A TTORNEYS.

Patented Oct. 29, 1940 PATENT OFFICE METHOD AND APPARATUS FOR PRODUCINGFIBROUS MATERIAL John H. Thomas, Perrysburg, and George M. Lannan,Newark, Ohio, assignors, by mesne assignments, to Owens-Coming FiberglasCorporation, a corporation of Delaware Application August 19, 1936,Serial No. 96,845 Renewed January 12, 1940 10 Claims.

The present invention relates to a novel method of producing longattenuated fibers and more particularly to an improved method andapparatus for causing a draft of gas to pull a stream of molten glassinto long attenuated glass fibers.

Heretofore, in the manufacture of glass wool or fibers, it has beencustomary to flow glass downwardly in stream form through suitableopenings and cause the stream to pass between or under the influence ofpressure jets or blasts of gas, which impinge upon the streams andattenuate them into fibrous form. When the streams are whipped about bythe blasts of gas during the cooling range, a relatively poor grade ofglass fibers is produced owing to the fact that the fibers tend to beunduly bent as they are solidifying and taking final form.

In other methods of producing fibrous glass,

4 a blast of gas is forcefully directed against a molten stream todisintegrate the stream into a mass of relatively short hairy fibers.These methods have various disadvantages, among them being a highconsumption of attenuating gases and the shortness of the fibersproduced.

The present invention aims to overcome the shortcomings notedhereinabove and to that end provides a method and apparatus for drawingfibers without the necessity of strong, positive pressure blasts ofgases.

Another object of the invention is to provide a method and apparatus fortreating a material which is capable of assuming a semi-fluid or viscouscondition and gradually increasing in viscosity and hardening whenpassed in stream formation and cooled or attenuated, such materialsincluding sugar, sealing wax, various other waxes, resin, rubber, orthermoplastic materials in general, and attenuating the same into finelong fila ments.

Another object of the present invention is to provide a method andapparatus for producing glass wool or other fibrous material and matsthereof in an inexpensive, simple manner.

Other objects and advantages of the present invention will becomeapparent from the following description taken in conjunction with thedrawing in which:

Fig. 1 is an elevational view, shown partly in section, of our improvedapparatus for producing attenuated fibers and causing them to form intomats or felts;

Fig. 2 is a diagrammatical fragmentary view of a conventional bushingfor emitting streams of 55 molten glass or other material and means forcausing an induction-of gases at predetermined pressures aroundthattenuating streams;

Fig. 3 is a view similar to Fig. 2 showing the induction means inanother position of adjustment; and 5 Fig. 4 is a fragmentary sectionalview of the hood shown in Fig. 1, the section being taken along the line4-4 of Fig. 1.

The present invention contemplates the provision of a method andapparatus for treating vari- 10 ous thermoplastic materials and othermaterials capable of assuming a semi-fluid or viscous condition andgradually increasing in viscosity and hardening when passed in streamformation and attenuated, such materials including glass, mo- 5 lasses,sugar, sealing wax and other waxes, resin, rubber, et cetera, saidtreatment contemplating emitting any of these materials in streamformation and then enveloping the stream in a smooth, regulable draft ofgases at suitable temperature 20 and pressure to attenuate and solidifythe stream into fine, long filaments of many times smaller diameter thansaid stream. In the specific embodiment disclosed, we have illustrated aconventional glass furnace capable of producing streams of molten glass,but it is to be understood that other materials as mentionedherein-above are also adaptable and capable of being reduced to finefilaments with the same method and apparatus, varying only thetemperatures and pressures as one skilled in the art would readilyunderstand.

Referring more particularly to the drawing, reference character 5designates a conventional glass furnace having a forehearth 6 extendingtherefrom, at the bottom of which are a plurality of discharge outletsI. Underlying each outlet 1 is a conventional V-shaped bushing 8 whichis preferably formed of platinum, orplatinum alloy, and electricallyheated, as illustrated and de- 0 scribed more fully in the co-pendingapplication for Letters Patent of Thomas and Fletcher, Serial No.56,222, filed December 26, 1935, which issued as Patent No. 2,165,318,July 11, 1939. Surrounding the bushing B is a refractory supporting mem-5 ber 9 which is separated from the forehearth B by the marginal flangeI0, formed integrally with the V-shaped bushing. Around the outerperiphery of the flange I0 is a cooling means I I adapted to freeze theglass in the vicinity of the outer edge of the marginal flange l0 andthus prevent leakage of glass from the bushing.

The bottom of the V-shaped bushing terminates, in a plurality of nippleopenings l2 which are relatively small and serve, to emit a plurality offine streams of molten glass ll. Spaced below the nipple openings I2 andthe refractory supporting members 9 are confining hoods 15, into whichthe molten streams M are projected. The lower ends of the hoods l5 leadinto a chamber l6 having at the bottom thereof a traveling foraminousbelt I! which is adapted to arrest the fibers in their downward passage.The hoods l5 are telescopically connected to the chamber l6 and areadjustably fastened thereto by screw bolts l8 or the like. Thistelescopic connection serves to permit the hoods [5 to be placed withina predetermined distance from the supporting members 9, the reasonstherefor being more fully set out hereinafter.

Arranged beneath the belt I! is a suction box 20 having a duct 2|leading to suitable suction producing means such as a blower or fan 22.At the front discharge end of the hood is an adjustable apron 23 whichoverlies the mat of glass wool fibers which is being conveyed out of thechamher by the belt H. The apron- 23 serves to sustain the vacuum causedby the fan 22 within the chamber I6.

The operation of our device contemplates maintaining a constant level ofmolten glass within the furnace 5 and the forehearth 6 over the bushings8. The temperature of this glass may be within optional limits accordingto the nature of the glass and the type of glass Wool which is to beproduced. We have found relatively high temperatures of about 2000 to2300 F. satisfactory, although, of course, these may be varied to suitparticular conditions. The electrically heated bushings 8 serve tomaintain the glass within the narrow limits of temperature which aredesired, and cause the glass to flow from the nipple openings in finestream. The diameters of the nipple openings are relatively small, theexact size, of course, being determined by the particular type and gradeof wool which is to be produced. As an example, it is possible toprovide nipple openings from about .125 inch to .150 inch for theproduction of filter wool, which is relatively coarse, having diameterswithin a range of about .005 inch to .013 inch. For finer types of woolranging in diameter size from .0001 inch to .0005 inch, smaller nippleopenings are preferable, the diameters of the openings being about in arange of .040 inch to .060 inch.

As the molten streams I4 immerge into the hoods I5, they are envelopedin relatively cool drafts of induced gases which are admitted throughthe intervening spaces or slots 25 between the upper edges of the hoodsl5 and the supporting members 9. The sub-atmospheric pressure in thesuction box 20 causes a partial vacuum to exist throughout the chamber16 and the hoods l5. This vacuum serves to increase the rate ofdischarge of the glass streams from the nipple openings l2. 7

We have found it possible to regulate the rate of production of theglass wool and the degree of attenuation of the fibers by regulating thesize of the slots 25 and the degree of vacuum in the suction box. Asshown in Fig. 2, the hood l5 has been raised to within a short distanceas, for example, within a fraction of an inch of the supporting members9. This causes a higher degree of vacuum to exist in the hoods l5 andalso causes a concentration of the draft between the hood and therefractory bushing whereby the glass fibers are attenuated at a higherrate and to a greater degree than when the width of the passageways 25is increased. In Fig. 3 the hood l5 has been shown somewhat lower inposition whereby the slot 25 has been increased to admit a larger amountof draft.

It will be noted that the present invention provides a method ofinducing a smooth flow of air around the fibers and at the same timecausing a high degree of vacuum to exist below the nipple openings, intowhich the glass streams are discharged. The draft of gas induced throughthe slots 25 envelopes the streams of glass during this period and coolsthe glass and thus causes said streams to freeze into fibers before theyhave had an opportunity to attenuate to too high a. degree. It will alsobe noted that the induced gases are the coolest at the point where theglass is the hottest, that is, at the nipple openings. This causes theglass to be rapidly cooled and permits the glass to be attenuated withina small range. The entire attenuation, however, may be effected prior tochilling of the fibers to solidity. The high temperature of the glass inthe bushings permits it to flow continually even though an end mayperchance break.

The fibers are carried downwardly through the hoods I5 and chambers 16by the enveloping draft and are forcefully disposed upon the belt I 'l.The suction within the box. causes the fibers to impinge upon and beheld against the belt, and thereby facilitates intertwining and feltingof the fibers. As the belt travels to the discharge end of the hood, afelted mass is gradually built up until it is completed at the dischargeend of the hood.

Modifications may be resorted to within the spirit and scope of theappended claims.

We claim:

1. The method of producing fibrous glass which consists in establishinga supply body of molten glass, projecting from said supply body a streamof said glass in a, semi-fluid or plastic condition, reducing thepressure below said point of projection and aroundsaid stream tosubatmospheric pressure and thereby causing the enveloping gasessurrounding said stream to flow concurrently with said stream and todraw it continuously to a single attenuated filament of a diametersmaller than said stream, and maintaining said sub-atmospheric pressurearound said stream until it is completely hardened.

2. The method of producing fibrous glass which consists in establishinga supply body of molten glass, projecting from said supply body a streamof said glass in a semi-fluid or plastic condition, reducing thepressure below said point of pro jection and around said stream tosub-atmospheric pressure and thereby causing the enveloping gassessurrounding said stream to fiow concurrently with said stream and todraw it continuously to a single attenuated filament of a diametersmaller than said stream, said stream being projected into a region ofpressure less than atmospheric, and said induced gases being caused tofiow at said reduced pressure, and maintaining said sub atmosphericpressure around said stream until it is completely hardened.

3. The method of producing fibrous glass which consists in establishinga supply body of molten glass, projecting from said supply body a streamof said glass in a semi-fluid or plastic condition, inducing surroundingatmospheric gases to impinge upon and to flow concurrently with saidstream and attenuate said stream to an attenuated filament of smallerdiameter than said stream, said stream being projected into a region ofpressure less than atmospheric, and said induced gases being caused toflow at said subatmospheric pressure, and maintaining saidsubatmospheric pressure around said stream until it is completelyhardened.

4. The method which comprises flowing a stream of viscous glass,inducing a draft of gas by suction and causing it to envelop said streamand apply to the stream a pulling force due to the kinetic energy ofsaid draft, of sufficient intensity to attenuate and draw the materialinto fine fibrous form, and maintaining said suction and resultingpulling force around said stream until it is completely hardened andattenuated.

5. Apparatus for producing fibrous glass which comprises a container formolten glass having openings in the bottom thereof adapted to emit amultiplicity of closely spaced streams of molten glass, a streamlineconduit closely spaced around and along the path of said streams havingan opening spaced apart from said container into which said streams areadmitted, means for exhausting the gases in said conduit and producing avacuum therein and causing surrounding atmospheric air to flow into theopening of said conduit and impinge upon said streams and flowconcurrently therewith to cause them to be attenuated into filaments,the said exhausting means being sufi'iciently remote from said containerthat the said vacuum is maintained around and along the length of saidstreams until they are completely hardened.

6. Apparatus for producing fibrous glass which comprises a container formolten glass having openings in the bottom thereof adapted to emit amultiplicity of closely spaced streams of molten glass, a streamlineconduit closely spaced around and along the path of said streams havingan opening spaced apart from said container into which said streams areadmitted, means for exhausting the gases in said conduit and producing avacuum therein to cause surrounding atmospheric air to flow into theopening of said conduit and impinge upon said streams and flowconcurrently therewith to cause them to be attenuated into filaments,the said exhausting means being sufiiciently remote from said containerthat the vacuum is maintained around and along the, length of saidstreams until they are completely hardened, and a foraminous belt insaid conduit upon which said attenuated filaments are arrested andintermatted to form a felted mass.

7. Apparatus for producing fibrous glass which consists in a bushinghaving openings in the bottom thereof adapted to emit streams of glass,a streamline conduit having the walls thereof closely spaced around andalong the path 01' said streams and having an opening spaced apart fromsaid bushing into which said streams are admitted, a foraminous beltmounted in said conduit remote from said opening, means for exhaustingthe gases under said belt and in said conduit and causing surroundingatmospheric air to be induced into the opening in said conduit atsub-atmospheric pressure and impinge against said streams and flowconcurrently therewith at a velocity greater than said streams to causesaid streams to be attenuated and cooled into fibrous form havingdiameters less than that of said streams, and then cause said inducedair to convey said fibers onto said belt while maintaining saidsub-atmospheric pressure around said streams until they are attenuatedand hardened and deposited upon said belt.

8. The method which comprises flowing a stream of viscous glass,inducing by suction through an open ended tube defining a column ofmoving gases a draft of gas at subatmospheric pressure and of suflicientforce and intensity to draw and attenuate said stream to fine fibrousform, introducing said stream into said draft and causing said stream tobe attenuated by the kinetic energy and force of said draft to finefibrous form, and maintaining said subatmospheric pressure around saidstream until it is completely hardened.

9. The method which comprises exhausting air from an open ended tubedefining a column of moving gases and thereby inducing an indraft ofatmospheric air into said tube space through an opening communicatingwith the atmosphere, introducing a stream of viscous glass through saidopening into said indraft of air and causing the stream of material tobe attenuated to a relatively fine filamentary form by the kineticenergy and force of said induced draft of air, and maintainingsubatmospheric pressure around said stream until it is completelyhardened.

10. The method which comprises flowing a stream of viscous glass from amolten supply body having an outlet orifice, inducing a column havinggreater length than width of moving gases by suction from a point remotefrom said outlet orifice and causing said column to envelop atsubatmospheric pressure said stream from a point substantially at theoutlet end of said outlet orifice and flow in the same direction as saidstream and apply to the stream a pulling force due to the kinetic energyof said column of sumcient intensity to draw and attenuate the materialinto fine fibrous form, and maintaining said subatmospheric pressure andresulting pulling force around said stream until it is completelyhardened and attenuated.

JOHN H. THOMAS. GEORGE M. LANNAN'.

